FR3043408A1 - PROCESS FOR THE TREATMENT OF LIGNOCELLULOSIC BIOMASS INCLUDING THE GASIFICATION OF A POWDER OF A WOOD RESIDUE FROM A BIOCHEMICAL PROCESS FOR THE TREATMENT OF LIGNOCELLULOSIC BIOMASS - Google Patents

Abstract

The invention relates to a method for treating lignocellulosic biomass including the gasification of a powdery woody residue. The woody residue is derived from a biochemical process for treating lignocellulosic biomass that includes a wet pretreatment stage, heating under acidic conditions and / or self-hydrolysis to produce a pretreated substrate. Said substrate, optionally separated from a liquid fraction, is subjected to enzymatic hydrolysis and is optionally subjected to fermentation that is separate or concomitant with hydrolysis, said fermentation being followed by distillation. The woody residue is separated downstream of the hydrolysis. It is dried and conditioned to obtain the woody powder residue whose particle size is between 15 and 900 μm, the water content less than 20% by weight, a grain density of between 500 and 900 kg / m3 and a minimum fluidization speed. is greater than zero and less than 0.15m / s. The powder, alone or as a mixture, is introduced into a fluidization gas at a speed greater than or equal to the minimum fluidization speed. The invention is particularly suitable for the production of synthesis gas, in particular in a biofuel production process.

Description

FIELD OF THE INVENTION

The present invention relates to a method for treating lignocellulosic biomass including the gasification of a woody powder residue which comes from a biochemical process of lignocellulosic biomass.

This powder is particularly well suited to the production of synthesis gas or "syngas" (containing in particular CO and H2) in a driven flow gasifier, with a view, for example, of its recovery in 2nd generation biofuel (bio-diesel from synthesis) thermochemically (also called "BTL" chain, acronym for the Anglo-Saxon term Biomass To Liquid). Any other use of the synthesis gas resulting from the gasification of this residue is within the scope of the present invention.

The woody residue produced according to the present invention is a co-product of the valorization of lignocellulosic biomass by the so-called biochemical path leading to the production of sugars and / or alcohols from the sugars present in the lignocellulosic biomass.

PRIOR ART

The production process of svnaas

The production of "syngas", in particular via a BTL pathway, and in particular in a driven flow gasifier, comprises, in a first step, a pretreatment of the native lignocellulosic biomass to reduce the charge in the form of a finely powdered powder. ground (between 50 and 200 μm) and easily fluidizable so as to allow pneumatic transport and injection of the biomass feed into the gasification unit, the operating conditions of which are typically a pressure P of between 20 and 45 bar (1 bar = 0.1 MPa) and a temperature T between 1200 ° C and 1600 ° C.

In the second gasification step, the carbonaceous material is partially oxidized in the presence of oxygen and water vapor in the gasification or gasification unit.

The present invention relates to the first step of pretreatment of lignocellulosic biomass. Since the gasification unit needs to be finely regulated and fed with a homogeneous solid charge flow rate, the pretreatment of the biomass is an essential phase to allow the smooth operation of the subsequent stages of fluidization and gasification.

The gasification can be carried out in a bed-type gasifier or a dry injection driven gasifier, that is to say a gasifier for the production of high T and P "syngas" by the dry route.

The principle of this technology, which is proven for fossil fuels such as coal, is based on the pneumatic transport of a pulverized charge to the inlet of a burner which is also supplied with oxygen and / or steam. water. When this technology is applied to lignocellulosic feedstocks, the main technical lock is the feed and pneumatic conveying system upstream of the gasifier.

This system is essentially a fluidized bed that operates in the homogeneous fluidization regime, with an inert gas, typically N2 or CO2. The pressure difference between this fluidized bed and the entrained gasifier allows pneumatic transport of the solid particles thereto. Once in the gasifier (P = 20-45 bar) the sprayed charge is gasified very rapidly (residence time of less than 2 seconds) to produce a syngas (in particular a mixture of H2 + CO) which can then be recovered by several different routes ( Fischer-Tropsch synthesis, methanation, hydrogen production ...). Other processes incorporate this technology for the gasification of biomass feeds. This is the case of the BTL (Biomass To Liquid) chain, which generally considers thermal and mechanical pretreatment of lignocellulosic biomass (torrefaction + grinding) before gasification.

Homogeneous fluidization involves an expanded bed but without creating bubbles to allow a continuous and stable supply to the gasifier burner. Moreover, it is also desirable to minimize the fluidization speed in order to limit the flow of inert gas which will be injected into the gasifier. The fluidization velocity is understood as the superficial velocity of the fluid, i.e. the ratio between the volume flow rate of gas and the section of the equipment in which the fluidization takes place, without taking into account the presence of the solid to be fluidized. The minimum fluidization speed is a specific characteristic of the solid powder which corresponds to the minimum flow rate of gas necessary for the fluidization of the powder. The minimum fluidization rate is measured according to ASTM Standard D7743-12 "Standard Test Method for Measuring the Minimum Fluidization Velocities of Free Flowing Powders".

The homogeneous fluidization regime corresponds to type A particles according to the Geldart classification (Ref: "Types of Gas Fluidisation", D. Geldart, Podwer

Technology, 7, pp 285-292, 1973) characterized by small diameter and density of the grain.

This classification applies mainly to spherical particles and does not take into account particles with very different form factors (fibrous particles).

However, the particles of lignocellulosic materials are characterized by their elongated shape which degrades the rheology of the system and makes fluidization of the bed difficult (creation of preferential passages, for example).

Regarding the case of the BTL chain, the biomass feedstock or lignocellulosic feedstock is most often available in the form of wood chips, wood chips which generally have the shape of parallelepipeds of typical dimensions 50 x 30 x 5 mm. Straw or other herbaceous residues can also be used as BTL chain feed, usually in the form of pellets or extrudates.

In a particularly interesting process, the filler, after a drying phase, is roasted. Roasting is a heat treatment between 200 ° C and 300 ° C in a non-oxidizing atmosphere which degrades the hemicelluloses mainly and a fraction of the cellulose and lignin.

This pretreatment weakens the fibers and facilitates the subsequent grinding so as to obtain a powder having better pneumatic transport properties. A pelletisation step (pelletization) of the roasted product may be necessary in the case of a decentralized configuration (the preparation of the feedstock and the gasification being in different sites), so as to densify the load with a view to its transport.

In the current state of knowledge, the roasting step has the following drawbacks: - Current roasting processes for this type of charges are still under development. Also, in this context, there is currently no mature commercial roasting process. It has been found that it can generate a loss of mass which can become significant, which significantly reduces the material yield of the complete chain. So some authors have been able to consider that the loss could go up to 30% while the specifications were reached ("BioTfueL Project: Targeting the

Development of Second-Generation Biodiesel and Biojet Fuels, J.-C. Viguié, N. Ullrich, P. Porot, L. Bournay, M. Hecquet and J. Rousseau, Oil & Gas Science and Technology - Rev. IFP New Energies, Vol. 68 (2013), No. 5). Existing roasting technologies do not allow very high capacities, and are limited to about 10 tM / h, expressed in tonnes of dry matter per hour. However, the capacity of an industrial BTL chain is of the order of 100 tMS / h, there is still a significant shift, up to a factor of 10. This is particularly detrimental for the economic balance of the chain in the case a centralized configuration since it would be necessary to multiply the number of roasting lines, with a very significant impact on the total investment cost.

In addition, the essential constraint of the roasting phase is obtaining a fine powder (about 100 μm) and with low fibrous particles (ratio width / length as close as possible to 1) so as to facilitate its flowability and its pneumatic transport in dense phase.

In the current state of development, roasting provides better properties than untreated powders, but does not completely solve the problems of powder transport.

Moreover, for the economics of the BTL chain, it is important to have high processing capacities in order to benefit from economies of scale on the gasifier.

However, because of the difficulties related to the collection of biomass (limited radius, sparse material, transport cost higher than for a liquid), the capacity of a BTL chain in biomass can be limited by the available resource. Industrial players are also considering the transformation of biomass into co-processing with other raw materials, notably coal or petcoke (same reference, BioTfueL article). This co-processing involves a certain flexibility of the equipment in place with several types of load and a harmonization of the properties of the loads coming from different sources when the limits of flexibility of operation of the equipment are reached. In general, dry injection driven flow gasifiers use pulverized coals whose particle size is of the order of 50 to 150 μm, this low particle size is made necessary to ensure a greater conversion of more than 90% in step gasification. In these ranges of particle size, the properties of the powder are very suitable for pneumatic transport by fluidization. The use of biomass feed poses other problems: the minimum particle size is no longer dictated by reactivity, because that of biomass is higher than that of coal allowing higher particle diameters, but by transport properties. Indeed, biomass has transport properties significantly degraded compared to coal on the one hand and secondly, in the absence of pretreatment, energy requirements related to grinding are higher for biomass than for coal, making it very energy-intensive to achieve particle size less than 1 mm or even 500pm.

To overcome these drawbacks, an industrial process has been sought in which the pretreatment of lignocellulosic biomass to produce synthesis gas (syngas) would not require roasting.

The present invention proposes to replace, in whole or in part, the roasted load derived from native lignocellulosic biomass by a woody residue powder resulting from a biochemical process for treating lignocellulosic biomass, in particular a biochemical process for producing biofuels .

The process of biochemical treatment of lignocellulosic biomass

The principle of the process of converting lignocellulosic biomass by biochemical processes uses a step of enzymatic hydrolysis of the cellulose contained in the plant material to produce glucose. Such methods are well known.

The glucose obtained can then be fermented into various products such as alcohols or solvents (ethanol, acetone, 1,3-propanediol, 1-butanol, isobutanol, 1,4-butanediol, etc.) or acids (acid acetic acid, lactic acid, 3-hydroxypropionic acid, fumaric acid, succinic acid, etc.). Today ethanol is the most studied product.

The process for the biochemical transformation of lignocellulosic materials into ethanol generally comprises a physicochemical pretreatment step, followed by an enzymatic hydrolysis step using an enzymatic cocktail, an ethanolic fermentation step of the released sugars and a step purification of fermentation products. An example is given by the document "Ethanol from lignocellulosics: A review of the economy", M. von Silvers and G. Zacchi, Bioresource Technology 56 (1996) 131-140.

Cellulose and possibly hemicelluloses are targets for enzymatic hydrolysis but are not directly accessible to enzymes. This is the reason why these substrates must undergo a pretreatment preceding the enzymatic hydrolysis step. The purpose of the pretreatment is to modify the physical and physicochemical properties of the lignocellulosic material, with a view to improving the accessibility of the cellulose trapped within the lignin and hemicellulose matrix. Various configurations exist for this pretreatment, as reported for example in the document "Production of bioethanol from lignocellulosic materials via the biochemical pathway: A review", M. Balat, Energy Conversion and Management 52 (2011) 858-875.

Pretreatments can be distinguished by their actions on the three major components of the lignocellulosic biomass cellulose, hemicellulose and lignin.

Pretreatments under acid conditions, by addition of an acid catalyst and / or by autohydrolysis of acid functions present in the biomass, will promote the accessibility of the cellulose by hydrolyzing the hemicellulosic part of the biomass.

The pretreatment may also include a mechanical action, especially by relaxation (steam explosion).

The pretreatment parameters include temperature, pressure, duration, presence of acid (type and concentration). These parameters act together on the progress of hydrolysis of hemicelluloses in the pretreatment reactor and on the resulting reactivity of the substrate produced. To a certain extent the effect of some parameters is interchangeable, for example, a longer duration can compensate for a lower temperature. These pretreatments have a limited action on lignin which remains predominantly in solid form. Other pretreatments operate in an alkaline medium and / or in a lignin solvent, such as the organosolv or alkaline processes, which aim at a separation of the lignin fraction by solubilization, which takes place, with generally a part of the hemicelluloses.

In order to convert the substrate to monomeric sugars, enzymatic hydrolysis is then conducted on the pretreated substrate (i.e. which contains the solid). It is performed using enzymes produced by a microorganism. The enzymatic solution added to the pretreated substrate contains enzymes that break down cellulose and hemicelluloses in solution of sugars containing in particular glucose.

The available sugars are then fermented to the product or products of interest, such as ethanol.

There are three main stages: enzymatic hydrolysis, fermentation of glucose (and by extension of C6 sugars such as mannose, galactose according to the properties of the strain), fermentation of xylose (and by extension of C5 sugars such as arabinose according to the properties of the strain).

These three steps can be conducted separately or concomitantly leading to different process schemes, this is discussed for example in the document "Assessment of Combinations between Pretreatment and Conversion Configurations for Bioethanol Production", Conde-Mejia et al., ACS Sustainable Chem . Eng. 2013, 1, 956-965.

Today, no configuration emerges as optimal, the evaluation being dependent on both the type of biomass considered, the pretreatment selected and biocatalyst specificities (enzymes and microorganism fermentaire) selected. Nevertheless, these configurations have in common that only sugars are valued in products of interest by fermentation.

After fermentation, a separation step takes place to recover the products. For example, this step may include distillation to concentrate the ethanol, the bottom of the column then containing a liquid-solid mixture which can be treated on a solid / liquid separation tool such as a filter press to obtain a cake containing the solid residual.

Thus, a by-product of biochemical biofuel production processes is the residual solid obtained after the enzymatic hydrolysis or fermentation or separation step, called the ligneous residue, which contains the fermentable non-recoverable lignin, residual polymers of sugars in cellulose or hemicellulose form present due to incomplete hydrolysis, as well as other non-fermentable compounds of the native biomass as part of the ashes. Depending on the configuration of the process used, this solid can be extracted at various points in the process diagram and in particular: after the enzymatic hydrolysis step, after the fermentation step or after the ethanol separation step.

In the current known schemes, this solid is recovered by combustion to supply energy (electricity) to the process as described in the document "Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol", Humbird et al., NREL / TP -5100-47764, May 2011 or in the aforementioned document by M. von Silvers.

In the patent application WO-14/091103, the solid having undergone enzymatic hydrolysis, and obtained in the distillation of the alcohol, undergoes a chemical treatment. This solid, optionally washed and dried, is fired in a medium comprising a hydrated inorganic salt. The residual solid is again subjected to enzymatic hydrolysis. The drying is carried out by any means known to those skilled in the art at a temperature of at least 20 ° C and such that the residual water content is less than 30% by weight.

Gasification and / or pyrolysis tests of the woody residue in different systems have been conducted. In particular, Ohrman et al. conducted pilot-scale tests on a flow gasifier driven at a gas pressure of 2 bar, described in "Pressurized oxygen blown entrained flow gasification of a biorefinery lignin residue", Ohrman et al., Fuel Processing Technology 115 (2013), pp 130-138. The woody residue produced was milled with a mill equipped with a grid at 750 μm. The stability of the gasification operation, carried out in less than 4 hours, was difficult with a total of three pilot stops. The first stop was after 64 minutes. Photographs of the gasifier show movements of the flame, which the authors attribute to slight variations in the feed of the load and the different sizes of particles present in it. The other two stops, although shorter, can be very clearly seen on the output gas compositions and the temperature in the reactor, and reflect an operation too unstable for acceptable operation on an industrial scale. On the other hand, the authors emphasize the need to reduce the amount of nitrogen introduced into the system, in particular to increase the efficiency of the system.

Also, it has been sought an industrial process of gasification (production of syngas) from a woody residue, which method does not have the aforementioned drawbacks, which is stable over time and which allows performance at least equal to those of the prior art without wood residue.

SUMMARY OF THE INVENTION

The present invention describes a process for the gasification of lignocellulosic biomass comprising a step of producing a powdery woody residue that can be injected into gasification without a prior roasting step and that makes it possible to overcome the disadvantages associated with this roasting technology. . In addition, the woody powder residue proposed in the present invention makes it possible to improve the transport properties of another powder thus facilitating the common treatment of the powders (co-processing). The use of this powdery wood residue has many advantages: it is not necessary to use a roasting step to prepare it; it lacks the fibrous nature of the native biomass; in particular, it can statistically present globally spherical particles, that is to say particles with a width to length ratio close to 1; it has excellent fluidization properties homogeneous by a gas (fluidization regime in which the gas velocity is between the minimum fluidization speed and the minimum bubbling rate). Thus, the powder obtained according to the process described in this patent, has the properties necessary for pneumatic injection, in particular in a driven flow gasifier. This allows the recovery of this residue to higher value-added products. this powder has a positive impact on the pneumatic transport properties when it is mixed with other lignocellulosic powders with less advantageous fluidization properties. Thus, it allows flexibility without additional cost and therefore to more easily value other charges. This also allows a broadening of the input charges of the gasification process. it can be used to feed a gasifier selected from a dry injection driven flow gasifier, a slurry feed driven gasifier, a fluidized bed gasifier or a moving bed gasifier; these different technologies lead to the production of a synthesis gas (syngas) more or less rich in methane, CO and H2 according to the operating conditions of the gasification. it is particularly suitable for supplying a dry-injected driven bed gasifier intended for the production of syngas containing mainly CO and H2, and having a very low content of methane and soot, these properties being in particular the consequence of parameters operating procedures (high temperature and pressure, short residence time) specific to this technology and well known to those skilled in the art. - when grinding is necessary, it requires less energy consumption than on native or roasted load, - the O / C and H / C ratios decrease compared to the original biomass, which means, according to the diagram from Van Krevelen, that the solid has properties closer to the reference solid fuel which is coal. The ICP of the residue is improved over that of the native biomass.

The woody powder residue according to the present invention draws its characteristics favorable to the fluidization in particular of the action due to the combination of: - a wet pretreatment of the lignocellulosic biomass which makes it possible to partially hydrolyze the hemicelluloses, - d an enzymatic hydrolysis of cellulose, which is the structuring sugar polymer of lignocellulosic biomass.

These steps are commonly encountered in processes for producing second generation biofuels (i.e. from lignocellulosic biomass) by the so-called biochemical pathway, in particular ethanol.

Under the combined actions of wet pretreatment and enzymes, the initial lignocellulosic biomass is completely destructured which allows, after drying and declogging or other mechanical treatment specified below, to obtain particularly favorable transport properties.

According to the present invention, preferably, the wood residue from the biochemical process does not undergo chemical treatment. He then undergoes only physical treatments.

More specifically, the invention relates to a process for treating lignocellulosic biomass comprising: a) a step of preparing a powder whose particle size is between 15 and 900 μm, preferably between 20-500 μm, having a lower water content; at 20% wt, a grain density between 500 and 900 kg / m3, and a minimum fluidization speed greater than zero and less than 0.15 m / s, preferably less than 0.1 m / s, b) -a fluidization stage at least a part of said powder, alone or as a mixture, by injecting a fluidization gas at a speed greater than or equal to the minimum fluidization speed of said powder, c) a step of injecting said fluidized medium in a gasification step to produce a synthesis gas containing CO and H2, and said step a) of preparing the powder comprises a biochemical treatment (steps A to D) with obtaining a woody residue and the treatment of the residue. woody (step E) with obtaining a powder: A) a step of pretreatment of lignocellulosic biomass carried out wet, by heating under acidic conditions and / or self-hydrolysis, a step which generates a pretreated substrate; preferably said pretreatment is a steam explosion under acidic conditions, B) an optional liquid / solid separation step of all or part of the pretreated substrate resulting from step (A) to obtain a liquid and a pretreated substrate containing the solid, C) -a step of enzymatic hydrolysis of the pretreated substrate resulting from step (A) and / or resulting from the optional step (B), carried out in the presence of cellulolytic or hemicellulolytic enzymes, C1 / C2) - optionally a fermentation step (C1), the hydrolysis and the fermentation taking place simultaneously or separately, and the fermentation being followed or not by a separation step (C2), D) - a solid separation step / liquid after enzymatic hydrolysis and / or, when they exist after fermentation or separation, with obtaining a woody residue, E) -a drying step so that its water content is less than 20% by weight, and conditioning said woody powder residue lacking fibrous character and having a particle size of between 15 and 900 μm.

Preferably, the woody powder residue further has a grain density between 500 and 900 kg / m3, a loading density between 200 and 400 kg / m3.

The drying is generally carried out at a temperature of 80-150 ° C.

Conditioning is a physical operation for separating the agglomerated particles, for example by demoulding and / or declogging and / or homogenization and / or grinding and / or pelletizing-grinding so as to obtain a powder whose particle size is between 15 and 900 μm, preferably between 20-500pm, having a water content less than 20 wt%, and a grain density of between 500 and 900 kg / m3.

The operating conditions of the stages of the biochemical treatment are conventional: step A) is carried out at a temperature of 120-250 ° C. and with a water content of the reaction medium of at least 35 wt.%, When it exists step B) optionally comprises a washing of the solid and / or a neutralization, - step C) is carried out at a temperature of 35-50 ° C, at a pH of between 4 and 6, in the presence of enzymes from a strain selected from the group consisting of Trichoderma, Aspergillus, Penicillium or Schizophyllum, Clostridium, preferably the strain is Trichoderma reesei, - when it exists, the fermentation (C1) is an alcoholic fermentation, preferably ethanol, carried out at a temperature of 25-40 ° C in the presence of a yeast Saccharomyces cerevisiae.

According to the invention, the woody residue in powder form is prepared without roasting. Advantageously, the ligneous residue resulting from stage D) of the process is not subjected to chemical treatment before stage E).

In an advantageous embodiment, the woody powder residue from step E) is conditioned in the form of pellets, pellets or extrudates, and then, before being fluidized, it is crushed to obtain said woody residue in powder form. This arrangement allows the transport and storage of the powdered residue.

In the context of the invention, the particle size of a powder is understood to mean the range of characteristic lengths of particles that make up this powder, such that 90% of the particles have a characteristic length greater than the low limit and 90% of the particles have a lower characteristic length. at the upper terminal.

DETAILED DESCRIPTION OF THE INVENTION

Step a) of preparing a particular powder whose particle size is between 15 and 900 μm, preferably between 20-500 μm, having a water content of less than 20% by weight, a grain density of between 500 and 900 kg / m3, and a minimum fluidization speed greater than zero and less than 0.15 m / s, preferably 0.1 m / s.

This step a) comprises a biochemical treatment (steps A to D) with obtaining a woody residue and the treatment of the ligneous residue (step D) to obtain said powder. The wet-pretreatment step A) of liano-cellulosic biomass to produce a pretreated substrate. The invention covers the cases where - all or part of the lignocellulosic biomass to be gasified undergoes the biochemical treatment, the woody powder residue being then mixed with the biomass to be gasified, the latter also being in powder form, obtained for example by roasting, the powdery wood residue comes from another lignocellulosic biomass, the woody powder residue being then mixed with the biomass to be gasified, the latter also being in powder form, obtained for example by roasting.

Biomass for Stage A is generally available in the form of wood chips or wood chips or straw. The size of the particles is typically between 5 and 500 mm, and preferably between 20 and 400 mm and even more preferably between 40 and 250 mm. Stage A comprises at least one stage of wet treatment, by heating and in acidic conditions and / or self-hydrolysis of the biomass generally carried out under the following conditions: temperature between 120 ° C. and 250 ° C. preferably between 160 ° C. and 200 ° C., carried out under acidic conditions and / or self-hydrolysis, the water content of the reaction medium is at least 35% by weight.

This step A can be implemented either discontinuously (batch) or continuously. Generally, the duration is between 30 seconds and 60 minutes, preferably less than 30 minutes. The purpose of the wet pretreatment step is to render the cellulosic matrix accessible to the enzymes used in the subsequent step (C) of enzymatic hydrolysis. When the lignocellulosic biomass is heated under humid conditions, partial hydrolysis of the acid functions present occurs. The wet pretreatment step (A) results in the partial solubilization of hemicelluloses (containing in particular C5 sugars) and the partial destruction of the fibers.

It may be preceded by a conditioning step including, for example, grinding, stone removal or the like. The pretreatment step according to step (A) of the process according to the invention can be carried out according to all types of pretreatment of lignocellulosic biomass under acidic conditions and / or of autohydrolysis known to those skilled in the art. The pretreatment step can be a thermal, chemical, mechanical and / or enzymatic treatment or a combination of these treatments. The acid-free steam explosion or the pretreatment by washing with very hot water are considered as acid pretreatments with regard to the present invention (pretreatments acting on the effect of self-hydrolysis).

For example, the pretreatment step (A) may be chosen from the steam explosion, with or without the presence of an acid catalyst (acid such as H2SO4), cooking under acidic conditions, treatment with water hot.

The pretreated solid substrate contains a solid fraction and a liquid fraction. Depending on the type of biomass treated, and the operating conditions applied, the solid fraction of the pretreated substrate is between 10% and 60% by weight, preferably between 30% and 50%.

Preferably, the pretreatment of step (A) comprises at least one steam explosion step, preferably in acidic medium.

In the steam explosion process, the lignocellulosic biomass is rapidly heated to high temperature (150 ° -250 ° C) by the injection of steam under pressure. This rise in temperature is followed by a sudden decompression, called detente or explosion, which destroys the lignocellulosic matrix.

The residence times vary from 10 seconds to a few minutes, for pressures ranging from 10 to 50 bars. Many configurations are possible to achieve the steam explosion.

The presence of acid improves the selectivity of the hydrolysis and makes it possible to retain a large proportion, typically more than 60%, of the hemicelluloses in the form of monomeric or oligomeric sugars in the liquid phase, while strongly limiting the formation of degradation products. such as furfural (from pentoses) and 5-HMF (from hexoses). The use of an acid catalyst makes it possible to reduce the process temperature from 150 ° C. to 200 ° C. against 250 ° C. for the steam-acid explosion, and thus to minimize the formation of degradation compounds.

The contacting of the acid catalyst with the biomass may be carried out by prior impregnation of the biomass with the acid and / or injection of the acid into the explosion reactor.

The contacting of the biomass and the acid catalyst is carried out by all the techniques known to those skilled in the art.

The operating conditions of the impregnation when it is carried out before the steam explosion are the following: the impregnation temperature is between 20 ° C. and 99 ° C., and preferably between 60 ° C. and 90 ° C. The acid used may be a mineral acid, of the H2SO4 type, or an organic acid such as acetic acid or formic acid. Preferably in the context of the present invention, the selected acid is H2SO4. The concentration of acid in the aqueous acid solution is between 0.01% by weight and 8% by weight and preferably between 0.02% by weight and 3% by weight, the contact time is from a few seconds to 24 hours; , preferably less than 12 hours and even more preferentially less than 2 hours.

In a particular implementation of the process, the introduction of the acid is done directly in the steam explosion reactor.

Depending on the content of MS at the end of the impregnation and that used in the subsequent step of steam explosion when the latter is separated, a step of reducing the liquid content of the impregnated mixture is performed. This separation is carried out by the known techniques of solid / liquid separation and can use for example a gravity flow, the application of a compression-type mechanical pressure, the application of a compacting pressure as in the case of the use of a filter press, or a vacuum undercap of the liquid such as with a vacuum belt filter, the application of centrifugal force, etc ...

The acid liquor recovered at the end of this separation may be wholly or partly recycled for impregnation.

Preferably, the solid phase introduced into the steam explosion, has an MS content (dry matter content expressed by weight) greater than 25%, and even more preferably greater than 40%. The separation can be carried out concomitantly with the introduction of the biomass impregnated into the steam explosion reactor. At the outlet of the explosion reactor, the mixture is expanded and a pretreated substrate containing the solid is recovered. Alternatively, a vapor phase may be separated for example by sending the mixture in a cyclone to separate a vapor phase at the head and the liquid and solid phases in the background. In another variant of the steam explosion, the expanded mixture is sent to a "blow-tank" with water injection to cool the mixture, there is no vapor phase. B) an optional liquid / solid separation step prior to enzymatic hydrolysis of all or part of the pretreated substrate resulting from step (A) making it possible to release: a solid fraction generally containing between 15% and 50% by weight of solid fraction, and preferably between 20% and 45% by weight of solid fraction, which joins the following steps (C) and (D) - a liquid fraction containing at least 60% by weight of the soluble sugars initially present in the substrate engaged in this step, preferably more than 75%, and more preferably more than 85% of soluble sugars (monomers and oligomers).

This step may comprise a washing of the solid and / or a neutralization of the acid.

This separation step of a liquid fraction and a solid fraction is positioned downstream of the pretreatment step (A), before the enzymatic hydrolysis. This step (B) can treat all or part of the pretreated substrate from step (A).

The sugars derived from hemicellulose and hydrolysed in step A, as well as the acid, if any, are present in the liquid fraction of the pretreated substrate at the output of step A). Depending on the MS of the pretreated substrate, it may be advantageous to separate a portion of the liquid fraction to increase the DM content for the subsequent steps of the process. Step (B) can also be used to extract a juice containing sugars from hemicelluloses to valorise them separately.

In the remainder of the text "pretreated substrate", the product resulting from step A) or the solid fraction resulting from step B) will be called indifferently, this substrate contains the solid.

Solid / liquid separation and optional washing can be accomplished by any of the techniques known to those skilled in the art.

The solid / liquid separation may use for example a gravity flow, the application of a compression-type mechanical pressure, the application of a compacting pressure as in the case of the use of a filter -press, or a vacuum draw off of the liquid such as with a vacuum belt filter, the application of centrifugal force, etc ...

A washing of the solid may be carried out by contacting the washing liquid with the pretreated substrate followed by a solid / liquid separation which may, for example, implement one of the following techniques: centrifugation, spinning or pressing, filtration, decanting. Washing can also be accomplished by displacement using technologies such as the band filter. This separation step can be repeated to obtain better washing performance.

The washing liquid can flow against the current of the solid in order to obtain good washing performance, while limiting the consumption of liquid phase.

Preferably, the washing liquid used contains more than 95% water.

The washing liquid can also be taken from one of the liquid streams of the downstream recovery process of C5 juice and / or sugars from step (C).

The washing ratio, defined as the ratio of the mass of washing liquid added to the mass of the liquid fraction of the pretreated substrate is between 1 and 10, and preferably between 1.5 and 4. The residual acid may be neutralized by the addition of a base in the liquid used for the washing and / or in the liquid phase recovered at the end of the washing. C) enzymatic hydrolysis step of the pretreated substrate from step (A) and / or optionally optional step (B), carried out in the presence of cellulolytic or hemicellulolytic enzymes.

A step of enzymatic hydrolysis of the pretreated substrate resulting from step (A) and / or optionally of the optional step (B) in which the substrate is brought into contact with a cocktail of cellulolytic and / or hemicellulolytic enzymes produced by a microorganism. Microorganisms, such as fungi belonging to the genera Trichoderma, Aspergillus, Penicillium or Schizophyllum, or anaerobic bacteria belonging for example to the genus Clostridium, produce these enzymes, notably containing cellulases and hemicellulases, suitable for the extensive hydrolysis of cellulose and hemicelluloses.

This step generally takes place under the following conditions: a continuous, discontinuous (batch) or fed-batch mode, a residence time generally of between 12h and 168h, and preferably between 24h and 144h and more preferably still less than 100h, - an initial concentration of solid material generally established between 5% and 25% by weight in the discontinuous and fed mode of embodiment, preferably between 7% and 20% by weight, and an average concentration of solid material between 5% and 15% wt in the continuous embodiment, a progress rate of cellulose hydrolysis at the end of the stage which is generally between 40% and 99%, and preferably between 50% and 95%, even more preferably more than 55%, the rate of progress is defined as the ratio between the amount of cellulose hydrolysed by the amount of cellulose input contained in the substrate has been pretreated, - a rate of progress of the hydrolysis of hemicelluloses of the native biomass of more than 50% over all of the steps A to C, and preferably more than 65% and more preferably more than 90%, the rate progress is defined as the ratio between the amount of hemicellulose hydrolysed by the amount of hemicellulose input contained in the native biomass, - preferably, the enzymes are derived from a strain selected from Trichoderma, Aspergillus, Penicillium or Schizophyllum Clostridium, preferably the strain is Trichoderma reesei, - the temperature is generally 35-50 ° C and the pH between 4 and 6, and preferably between 4.5 and 5.5 and preferably between 4.8 and 5.2 .

The enzyme-producing microorganism can be produced in an independent production line that can be performed on-site or off-site.

Very preferably, the microorganism used is Trichoderma reesei.

Cellulases, respectively hemicellulases, hydrolytically transform cellulose, or hemicellulose respectively, into sugars that can dissolve in the aqueous phase. In step (C), the conditions of the enzymatic hydrolysis, mainly the combination of the solids content of the mixture to be hydrolysed, the amount of enzymes used and the duration, are chosen so that one obtains a solubilization of the cellulose between 40% and 99% by weight, preferably between 50% and 95% by weight relative to the total weight of cellulose contained in the pretreated substrate. C1) Optional fermentation step

According to a variant of the process, an optional fermentation step of the sugars present in the hydrolyzate from step (C) is carried out. Step C1 is the step of fermentation by a microorganism of the hydrolyzate obtained at the enzymatic hydrolysis. The fermentable sugars are thus converted into alcohols and / or solvents and / or acids or other products of interest by yeasts or other microorganisms.

The fermentation is most often carried out at a temperature between 25 ° C and 40 ° C, most often between 30 ° C and 37 ° C. At the conclusion of this step, a fermentation broth comprising suspended solids and a liquid phase in which the desired product or products (alcohols and / or solvents) is found. Step (C1) has no impact on the particle size of the solid present.

When the steps of enzymatic hydrolysis (C) and alcoholic fermentation (C1) are carried out simultaneously in the same reactor, it is called SSF (Simultaneous Saccharification and Fermentation).

When the enzymatic hydrolysis of sugar polymers is simultaneously carried out and the fermentation of glucose and xylose is carried out, it is called SSCF (Simultaneous Saccharification and Co Fermentation).

In the SSF and SSCF process, the temperature is chosen within the temperature range of the fermentation, usually between 30 ° C and 37 ° C.

The microorganism (s) used in step (C1) may be chosen for example from the following elements: yeasts of the genus Saccharomyces, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Saccharomyces uvarum, Saccharomyces diastaticus, Kluyveromyces fragilis, Candida shehatae, Pichia stipitis , Pachysolen tannophilis or bacteria of the genus Zymomonas mobilis, Clostridium, Escherichia coli.

The fermentation products are preferably alcohols (alcoholic fermentation) such as, for example, ethanol, acetone, butanol, isobutanol, isopropanol, etc., alone or as a mixture, alcohol-sugars such as xylitol and / or solvents (ABE fermentation).

The products can also be acids such as succinic acid, lactic acid or fatty acids.

Preferably, the product of the fermentation of sugars in step (C1) is ethanol, it is an ethanol fermentation.

Preferably, the microorganism used in step (C1) is a yeast of the genus Saccharomyces cerevisiae, preferably used in ethanolic fermentation.

Thus, preferably, the fermentation (C1) is an alcoholic fermentation, preferably ethanol, carried out at a temperature of 25-40 ° C, in the presence of a yeast Saccharomyces cerevisiae. C2) Optional step of separation of the fermentation product

According to this variant of the process, an optional step of separation of the product of the fermentation of the sugars of step (C1) is carried out. Step (C2) is a separation / purification step of the product which makes it possible to obtain a purified product (alcohol, etc.). This separation can be carried out for all techniques known to those skilled in the art and will be adapted according to the physicochemical and thermodynamic properties of the product to be separated. This separation can implement in particular distillation techniques, liquid-liquid extraction, membrane processes, molecular sieves, etc. This separation is preferably by distillation, especially in the case of alcoholic fermentation.

In addition to the desired product, a cake containing the lignin (described below) is also obtained at separation (for example distillation). D) a liuid / solid separation step placed downstream of step (C)

This solid / liquid separation step must be carried out on a solid resulting from a pretreatment under acidic conditions (as defined above) and having undergone enzymatic hydrolysis (as defined above).

This solid / liquid separation step can be more precisely carried out - in the case where there is no fermentation or other treatment: immediately after enzymatic hydrolysis (step C) - in the case where there is a fermentation (step C1 ): - when (C) and (C1) are carried out separately: between steps (C) and (C1) - when (C) and (C1) are carried out concomitantly: between steps (C1) and ( C2) - when (C) and (C1) are carried out separately or concomitantly: in step (C2) or downstream of step (C2).

This separation takes place on all or part of the flow at the output of step (C), and preferably all, making it possible to recover generally more than 80%, and more preferably more than 85% and even more preferably more than 90%. of the solid fraction engaged at this stage.

It can be performed by any technique known to those skilled in the art. For example, it can use a gravity flow, the application of a compression-type mechanical pressure, the application of a compacting pressure as in the case of the use of a filter press, or a vacuum draw-off of the liquid such as with a vacuum belt filter, the application of a centrifugal force, etc.

The current limits of the solid / liquid separation equipment lead to the presence of a portion of the liquid phase in the cake extracted, between 25 and 80% by weight. The extraction step of the solid residue can be carried out immediately after the enzymatic hydrolysis step (C). In this case, the cake extracted comprises, on the one hand, a liquid phase comprising between 75 and 99% by weight of water, and sugars and, on the other hand, solid residues, comprising unhydrolyzed cellulose, unhydrolyzed hemicelluloses. , lignin and other insoluble compounds initially present in the substrate.

According to another embodiment of the process according to the invention, the step of extraction of the solid residue can be carried out between C1 and C2, or immediately after the fermentation step (step C1). In this case, the cake extracted comprises on the one hand a liquid phase comprising between 75% and 99% by weight of water, alcohols and / or solvents (products) and unconverted sugars; and on the other hand, solid residues, comprising unhydrolyzed cellulose, unhydrolyzed hemicelluloses, lignin and other insoluble compounds initially present in the substrate; as well as a quantity of alcoholic microorganisms (between 2% and 20% depending on the performance of the enzymatic hydrolysis and the alcoholic fermentation).

According to another embodiment, the step of extracting the solid residue is carried out after the separation / purification step (step C2). In this case, the cake extracted comprises on the one hand a liquid phase comprising between 80 and 99% by weight of water, unconverted sugars and traces of products (less than 0.1%); and on the other hand solid residues, comprising unhydrolyzed cellulose, unhydrolyzed hemicelluloses, lignin and other insoluble compounds initially present in the substrate; as well as a small amount of alcoholic microorganisms (between 2% and 20% depending on the performance of the enzymatic hydrolysis and the alcoholic fermentation).

It should be noted that the solid and liquid phase separations used in the context of the present invention (steps B, D) generally lead to two flows: - A so-called liquid phase which contains liquid and possibly a small portion solid, typically less than 5% by weight solids, and preferably less than 1% solids, - a so-called solid phase which contains most of the solid and a liquid fraction. Typically, the solids content of this phase is between 10% and 60% by weight, preferably between 30% and 50%.

The presence of liquid in the solid phase is due to the limitations of existing solid / liquid separation equipment on industrial units. The solid / liquid separation step may optionally be coupled to a washing in a manner similar to the washing described above.

By step D) is meant a separation step of the biochemical process which may comprise one or more enzymatic hydrolyses. E) a step of drying and optionally conditioning the solid (or woody residue) from the separation step (D).

A drying phase is essential to remove the wet fraction of the solid resulting from the separation step (D), and to obtain a dry powder transportable by pneumatic means for injection into the entrained gasification unit.

The solid leaving the separation step (D) is dried using any drying technique known to those skilled in the art. It can be dried for example in an oven turning with hot air. The drying is carried out at a temperature of between 80 ° C and 150 ° C, more preferably between 100 ° C and 125 ° C.

The product at the outlet of the drying phase has a water content of less than 20% by weight, and preferably between 0.5% and 10% by weight, or else 3-10% by weight.

The conditioning of the solid can take place before, during or after drying. Its objective is to obtain a powder having the desired characteristics, in terms of particle size, humidity, minimum speed of fluidization.

The packaging serves to break any agglomerates of particles formed during the separation and drying steps as well as to reduce the size of the particles in the event that they are not specified for the gasification. The conditioning also serves to homogenize the solid. Homogenization is the process of mixing the particles to obtain a product with uniform characteristics.

This conditioning can be done by any physical operation to separate the agglomerated particles (mowing or "uncaking", declogging); this operation is sufficient in some cases, otherwise it can be coupled with grinding. These operations are well known to those skilled in the art.

Demoulding is particularly necessary in cases where the separation step (D) is carried out with a filter press at the output of which a compact solid cake is obtained.

A crushing grinding or any other method known to those skilled in the art (shear, impact ...) may be necessary depending on the type of biomass and the conditions of the treatment.

The packaging can in a very particular case become useless if, depending on the nature of the biomass used and the operating conditions of the separation and drying, the particle size of the biomass at the outlet of said drying step is suitable for introduction into the gasifier.

An optional step of densification of the solid resulting from the drying step can be used so as to obtain granules, extruded pellets or pellets that can be stored or transported, and then requiring a subsequent grinding step to return to a fine and fluidizable powder as defined in the invention. This step is interesting especially in the case of decentralized configuration (the pretreatment unit and the gasification unit are not on the same site).

This densification makes it possible to reduce transport costs and avoids the safety risks (explosion) related to the transport of a powder charge. Thus, densification can also be useful even in the case of centralized configuration for storage requirements.

The presence of a densification step necessarily induces a subsequent grinding step to return to a fine and fluidizable powder as defined above.

The product at the outlet of step (E) is a finely divided dry powder and having physical and fluidization properties suitable for transport in a gasification step: a particle size typically between 15 and 900 μm, and preferably between 20 μm and 500 μm and even more preferably between 30 and 300pm, particles having no fibrous character, i.e. at least 90% of the particles have a form factor, defined as the width-to-length ratio of the near particle of the unit, from 0.3 to 1, preferentially greater than 0.5 and even more preferably greater than 0.8, a moisture content of less than 20 wt.%, and preferably of between 5 and 10%, preferably a density of grain between 500 and 900 kg / m3, and preferably between 600 and 700 kg / m3, - preferably, a loading density (bed density) of between 200 and 400 kg / m3 and preferably between 250 and 350 kg / m3 for the powder used alone, a minimum low fluidization speed, greater than zero and less than 0.15 m / s and preferentially less than 0.10 m / s and even more preferably less than 0.05 m / s, or even less than 0.012m / s, - a homogeneous fluidization corresponding to a powder of type A according to the Geldart diagram, without formation of bubbles or preferential passages.

In addition, particularly advantageously, this powder has an ability to improve the fluidization of other powders.

Indeed, it has been found that the powder obtained according to the present invention makes it possible, when mixed with other feedstocks to be treated with poorer fluidization characteristics, to improve the fluidization behavior of the mixture, by lowering the minimum fluidization speed.

The proportions of powder and filler to be treated are determined, for example by testing, so that the minimum fluidization speed of the mixture is greater than zero and less than 0.15 m / s, and preferably less than 0.1 m / s and less than that of the load to be treated alone. These proportions vary according to the characteristics of the load to be treated and the wood residue powder.

The charge to be treated is in the finely divided state (such as entering gasification); it may be raw or pretreated lignocellulosic biomass (such as roasted biomass, biomass exploded with steam, etc.) or another material (coal, petroleum coke, etc.) as is explained hereinafter.

The powder thus obtained (alone or as a mixture) is then fluidized in a step b).

Thus, the powdered woody residue may be fluidized in admixture with at least one other lignocellulosic biomass powder and / or with at least one other powder of fossil origin.

Steps b) of fluidization of the powder and step c) of injection under pressure in the gasification step (step c)

The powder thus obtained can be easily fluidized and transported pneumatically in gasification, and for example to a driven flow gasifier for the production of synthesis gas at high pressures.

It is possible to feed the gasifier 100% with woody powder according to the invention or co-processing with another material also in highly divided form.

The co-processing can be understood in several ways: - on campaign: a single charge is treated for a period of time at the end of which a new charge is treated - co-processing with separate injections: 2 charges are injected in same time but have 2 separate injection circuits because of the fluidization characteristics too different between the 2 charges - coprocessing with co-injection: the 2 charges are mixed, fluidized and injected together in the gasifier.

The product according to the present invention allows these 3 types of co-processing, thus ensuring greater flexibility in the installation.

The co-processing of the powder according to the present invention can be carried out with all the charges intended for the gasifier. For example, the co-processing can be carried out with powders of coal, petcoke or any other type of pretreated or raw biomass powder. The powder according to the present invention can be treated with fillers having fluidization properties better or worse than it.

When the powder is thus treated with a filler having lower fluidization properties, the fluidization properties of the mixture can be improved over those of the filler alone. In particular, the minimum fluidization speed is decreased or even greatly reduced, depending on the mass percentage of the mixture. Preferably, when the minimum fluidization speed of the powder to be co-processed is less good than that of the powder according to the present invention, this minimum speed remains less than 1 m / s and preferably less than 0.8 m / s, and even more preferably less than 0.3m / s.

The material of the load is therefore also in very divided form. Its particle size is generally in the same range of values as the woody residue powder. Preferably, the powder to be co-processed has a particle size of typically between 15 and 900 μm. Even more preferably, when the powder to co-process is derived from fossil resources such as typically coal or petroleum coke, it has a particle size of between 15 and 400 μm, and more preferably between 25 and 200 μm. When the powder to co-process is derived from biomass, raw or after a first treatment, it has a particle size of between 50 and 900 pm, and more preferably between 100 and 600 pm.

Thanks to the woody residue powder, it has been advantageously possible to operate with a material having a larger particle size than in the prior art (around 100 μm), the choice being made to fulfill the minimum fluidization speed criterion, as well as that has been previously described.

The woody residue in powder form can be fluidized in a mixture with at least one other lignocellulosic biomass powder. It can be the load to be treated or another material. This is for example the raw biomass or pre-treated biomass for example roasting, steam explosion, or other.

The woody residue in powder form can be fluidized in admixture with at least one other powder of fossil origin, for example coal, petroleum coke (or "petcoke"). Petroleum coke is a co-product of oil refineries.

The powder thus obtained can be introduced into a gasification step producing syngas, selected from dry injection driven flow gasification, slurry fed flow gasification, fluidized bed gasification or moving bed gasification.

It is particularly suitable in a dry injection driven flow gasification stage.

In the case of a flow-through gasifier, the fluidization in the injection system takes place at pressure conditions higher than the target pressure in the gasifier to ensure the flow of the fluidized product to the gasifier and compensate the pressure drops in the transport and injection systems. Preferably, the fluidization takes place at a pressure of between 2 bar and 120 bar, and preferably 5 bar and 80 bar and even more preferably between 12 bar and 50 bar. The fluidization gas is generally an inert gas used for this purpose, for example nitrogen, carbon dioxide, etc.

The higher the pressure in the fluidization stage, the greater the interest to use a powder having a low minimum fluidization rate. Indeed, the fluidization takes place for a volume flow rate of gas fixed according to the properties of the powder. The lower the minimum fluidization speed of the powder, the smaller the flow rate of gas required for fluidization and maintaining a steady state. As the pressure increases, the density (in kg / m3) of the gas also increases. At a fixed volume flow rate of gas therefore correspond to much higher mass and molar flow rates as the pressure increases. For industrial systems operating at high pressure, and typically more than 12 bars, treating a powder having a low minimum fluidization speed makes it possible on the one hand to reduce the consumption of inert gas (as well as its cost of compression), but also of to limit the molar dilution of the syngas by the inert gas of fluidization, and thus to limit the size of the downstream equipment of treatment of the syngas.

In gasification, and in particular in a driven flow gasifier, it is generally carried out at a pressure of 20-80 bar and a temperature of 1200-1600 ° C. In fluidized-bed or moving-bed gasification technologies, generally lower temperatures are used, typically below 1000 ° C. Gasification produces a syngas that is subsequently processed for the production of biofuels or other chemicals, or for energy use in combined cycle plants, for example.

The process according to the invention is particularly well suited to lignocellulosic biomass treatment processes which use a gasification step producing a syngas rich in CO and H2 and whose objective is the production of biofuels (i.e. at least partly derived from biomass).

Fluidization and gasification techniques are conventional and known to those skilled in the art. The invention has another important advantage industrially: the powdered wood residue is easily formed into pellets or extruded, or other form. It can then be easily transported in this form to another site, or stored. By simple grinding, it is again obtained the powder having the characteristics described for the fluidization.

The figures The invention is illustrated by the following figures.

Figure 1 attached represents a block diagram of the process for producing a woody powder residue according to the invention.

The optional steps are presented in dotted lines.

The steps of the process of the biochemical process for the preparation of the ligneous residue are recognized in FIG.

The lignocellulosic biomass (1) undergoes a pretreatment step (A) wet. Preferably, but not necessarily, the pretreated substrate (2) is subjected to a separation step (B) of the liquid (3), in which optionally the solid fraction is washed and neutralized, the solid fraction is then sent (line 4 ) in the step (C) of enzymatic hydrolysis. In the absence of step (B), the pretreated substrate (2) is sent directly to step (C). The effluent (5) resulting from the enzymatic hydrolysis is according to FIG. 1 subjected to the liquid separation step (D) (6) and the solid woody residue (7) is obtained.

Figure 1 also shows schematically the step (E) of drying and conditioning of the ligneous residue (7), so as to obtain a woody powder residue (8) having the characteristics according to the invention. This residue (8) is then subjected to the fluidization step (b) in the reactor (9), the fluidization gas is injected through the pipe (10). The fluidized medium (11) is then able to be injected into the gasifier in the injection step (12).

The conditions of these steps are those described above.

FIG. 2 represents a block diagram of a particular embodiment of production of a woody powder residue according to the invention, the residue being obtained in a biofuel production process (BTL). We recognize the steps described above. The process further comprises the steps of: C1) fermentation step of the sugars resulting from the hydrolysis of the biomass C2) distillation stage of the wine resulting from the fermentation. The effluent (5) resulting from the enzymatic hydrolysis is fermented in a fermentation step (C1), which may or may not be separated from the enzymatic hydrolysis (known methods).

A fermented effluent (13) is obtained, which is generally distilled (step C2) to separate the desired product (14), for example ethanol.

In this embodiment, the liquid / solid separation step (D) may be situated between steps (C) and (C1) to separate the liquid (6) from the effluent resulting from the enzymatic hydrolysis. of the ligneous residue (7) - this is the embodiment of FIG. 1-, or - between the steps (C1) of fermentation and (C2) of distillation, to separate from the effluent (13) the liquid (6) the wood residue (7), or - downstream of the distillation step (C2) to separate from the cake (15) the liquid (6) of the wood residue (7).

The conditions of these steps are those described above.

EXAMPLES

Example 1

The treated feedstock is raw straw of the following composition, at a rate of 80 kilograms (kg) of raw straw / hour.

The contents below are given in% by weight.

This straw is first milled at 50mm in a packaging workshop (unraveling, stone removal, grinding 50mm). The material losses in this workshop are 2.5% weight.

The straw is then impregnated with an acid solution whose pH is 1.1 and then introduced into a continuous steam explosion reactor. The conditions of the steam explosion are as follows: residence time 6 minutes, temperature 175 ° C. At the exit of the explosion reactor, the mixture is expanded and passes through a cyclone allowing the separation of a vapor phase and a mixed solid / liquid phase which is pretreated straw.

The pretreated straw is neutralized and then introduced into an ethanol conversion unit in which the pretreated straw is diluted to 23% DM and placed in contact with an enzymatic solution and a yeast of the Saccharomyces type genetically modified to ferment the xylose.

The conditions of implementation make it possible to obtain an ethanol / sugar yield of 0.41 g of ethanol / g of sugars (glucose + xylose). The rate of progress of the hydrolysis of cellulose, defined as the ratio between the amount of cellulose hydrolysed by the amount of cellulose input contained in the pretreated substrate, is 88%. The rate of progress of hydrolysis of hemicelluloses, defined as the ratio between the amount of hemicellulose hydrolysed by the amount of hemicellulose input contained in the native biomass, is 84%. After this step, 286 kg / hour of fermentation wine are sent to a distillation unit which produces: 18.2 kg / h of a concentrated ethanol solution at 92% by weight and 268.2 kg / h of vinasses .

The vinasses are sent in a solid / liquid separation step carried out by filter press. After the solid / liquid separation, clear vinasses are obtained which are treated in a wastewater treatment unit to remove the majority of the soluble organic matter before rejection.

The solid cake consists of 41% solids, 56.8% water and 2.2% soluble material. This cake is dried at 105 ° C in a drying step which allows to retain 100% of the solid and 85% of the soluble material while removing 99% of the water. The solid is then demolded to separate the aggregates of particles. 25 kg / hour is thus obtained of a finely divided solid phase of composition:

This solid phase has a particle size between 60 and 400 μm and has a fluidization rate of 0.012 m / s without the need for additional grinding; it is an ideal load for a gasification process.

The charge is used in a syngas production process. The solid fuel is extracted from the storage hopper and dosed by a variable speed gravimetric feeder. It is then introduced by gravity into a first pressurizing hopper.

After upstream and downstream isolation, the hopper is pressurized to 35 bar using nitrogen. Once the required pressure is reached, the downstream valve opens and the product is transferred to a second hopper from which it is fluidized and then conveyed pneumatically in dilute phase to the gasifier which is operated at 32 bar.

The other operating conditions of the gasifier are conventional for this type of technology.

Pressurization and fluidization being done in batch mode on an injection line, several injection lines are operated in parallel to ensure continuous supply of the gasifier.

Example 2

The powder produced in Example 1 having a particle size of between 60 and 400 μm and a fluidization speed of 0.012 m / s is treated (co-processed) in co-injection with roasted and ground beech having a particle size of between 90 μm and 600 μm. and a minimum fluidization rate of 0.080 m / s. The flow rates are 25 kg / hour of powder produced according to the invention and 20 kg / hour of roasted beech, a total of 45 kg / hour of mixture to be fluidized.

The resulting mixture has a minimum fluidization rate of 0.020 m / sec. The solid mixture is extracted from the storage hopper and dosed by a variable speed gravimetric feeder. It is then introduced by gravity into a first pressurizing hopper. After upstream and downstream isolation, the hopper is pressurized to 30 bar using nitrogen. Once the required pressure is reached, the downstream valve opens and the product is transferred to a second hopper from which it is fluidized and then conveyed pneumatically in dilute phase to the gasifier which is operated at 28 bar. The operating conditions of the gasifier are conventional. Pressurization and fluidization being done in batch mode on an injection line, several injection lines are operated in parallel to ensure continuous supply of the gasifier.

Claims (15)

1. Process for treating lignocellulosic biomass comprising: a) a step of preparing a powder whose particle size is between 15 and 900 μm, preferably between 20-500 μm, having a water content of less than 20% wt. , a grain density between 500 and 900 kg / m 3, and a minimum fluidization speed greater than zero and less than 0.15 m / s, preferably less than 0.1 m / s, b) - a step of fluidizing a part at least of said powder, alone or as a mixture, by injecting a fluidizing gas at a speed greater than or equal to the minimum fluidization speed of said powder, c) a step of injecting said fluidized medium into a step of gasification to produce a synthesis gas containing CO and H2, and said step a) of powder preparation comprises a biochemical treatment (steps A to D) with obtaining a woody residue and the treatment of the ligneous residue (step E) with obtaining of powder: A) a step of pretreatment lignocellulosic biomass carried out wet, by heating under acidic conditions and / or self-hydrolysis, step that generates a pretreated substrate; preferably said pretreatment is a steam explosion under acidic conditions, B) an optional liquid / solid separation step of all or part of the pretreated substrate resulting from step (A) to obtain a liquid and a pretreated substrate containing the solid, C) -a step of enzymatic hydrolysis of the pretreated substrate resulting from step (A) and / or resulting from the optional step (B), carried out in the presence of cellulolytic or hemicellulolytic enzymes, C1 / C2) - optionally a fermentation step (C1), the hydrolysis and the fermentation taking place simultaneously or separately, and the fermentation being followed or not by a separation step (C2), D) - a solid separation step / liquid after enzymatic hydrolysis and / or, when they exist after fermentation or separation, with obtaining a woody residue, E) -a drying step so that its water content is less than 20% by weight, and conditioning said woody powder residue lacking fibrous character and having a particle size of between 15 and 900 μm. 2. The method of claim 1 wherein the woody powder residue further has a grain density between 500 and 900kg / m3, a loading density between 200 and 400 kg / m3. 3. Method according to one of the preceding claims wherein the drying takes place at a temperature of 80-150 ° C. 4. Method according to one of the preceding claims wherein the packaging is a physical operation for separating the agglomerated particles, for example by cutting and / or declogging and / or homogenization and / or grinding and / or pelletizing-grinding to obtain a powder whose particle size is between 15 and 900 μm, preferably between 20-500 μm, having a water content of less than 20% by weight, and a grain density of between 500 and 900 kg / m3. 5. Method according to one of the preceding claims wherein - step A) is carried out at a temperature of 120-250 ° C and with a water content of the reaction medium of at least 35 wt%, - when B) optionally comprises a washing of the solid and / or a neutralization, - step C) is carried out at a temperature of 35-50 ° C., at a pH of between 4 and 6, in the presence of enzymes derived from a strain selected from the group consisting of Trichoderma, Aspergillus, Penicillium or Schizophyllum, Clostridium, preferably the strain is Trichoderma reesei. 6. Method according to one of the preceding claims wherein step D) is carried out: - in the case where there is no fermentation or other treatment: immediately after enzymatic hydrolysis (step C) - in the case where there is a fermentation (step C1): - when (C) and (C1) are carried out separately: between steps (C) and (C1), - when (C) and (C1) are carried out concomitantly between steps (C1) and (C2), - when (C) and (C1) are carried out separately or concomitantly: in step (C2) or downstream of step (C2). 7. Method according to one of the preceding claims wherein the fermentation (C1) is an alcoholic fermentation, preferably ethanol, carried out at a temperature of 25-40 ° C in the presence of a yeastSaccharomyces cerevisiae. 8. Method according to one of the preceding claims wherein the woody residue powder is prepared without roasting. 9. Method according to one of the preceding claims wherein the ligneous residue from step D) of the process does not undergo chemical treatment before step E). 10. The method as claimed in claim 1, wherein said gasification step is carried out in a dry injection driven flow gasifier, or a slurry-fed driven stream, or a fluidized bed, or a moving bed. 11. The method of claim 10 wherein said gasification step is performed with a driven bed at a pressure of 20-80 bar and a temperature of 1200-1600 ° C. 12. Method according to one of the preceding claims wherein the woody powder residue is fluidized in a mixture with at least one other lignocellulosic biomass powder. 13. Method according to one of the preceding claims wherein the woody powder residue is fluidized in a mixture with at least one other powder of fossil origin. 14. Method according to one of the preceding claims wherein the woody powder residue from step E) is packaged in pellets or extruded, and before being fluidized, it is ground to obtain said powdered residue . 15. Method according to one of the preceding claims wherein the gasification produces a syngas later treated for the production of biofuels or other chemicals, or for energy use in combined cycle plants.